Re: how can one use mathematica get the approximate derivative of {x,y} data points?

• To: mathgroup at smc.vnet.net
• Subject: [mg124235] Re: how can one use mathematica get the approximate derivative of {x,y} data points?
• From: "Nasser M. Abbasi" <nma at 12000.org>
• Date: Sat, 14 Jan 2012 17:05:54 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```On 1/14/2012 1:55 AM, Michael B. Heaney wrote:
> Hi,
>
> I have a set of {x,y} data points:
>
>   {{0.03512, -0.5}, {0.0351181, -0.499}, ... {-0.113972, 0.699}, {-0.115072,
> 0.7}}
>
> These data points look like a function y=f(x) when plotted on the x-y axes.
> However, I do not know what the function f(x) is. But I need to get the
> approximate derivative df/dx, as another set of data points. How can one
> use Mathematica to do this?
>
> Thanks,
>
> Michael
>
> --

one way:

?Fit

data = {{0.03512, -0.5}, {0.0351181, -0.499}, {-0.113972,0.699}, {-0.115072, 0.7}}
f = Fit[data, {1, x, x^2}, x];
D[f, x]

--Nasser

```

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